Examination of the laryngeal musculature and recurrent laryngeal nerves ofzebra (Equus burchelli) for evidence of idiopathic laryngeal hemiplegia

Aims: This study was undertaken in order to determine whether wild Burchell 's Zebra (Equus burchelli) are affected by Idiopathic Laryngeal Hemiplegia (ILH). ILH has a high prevalence in the domestic horse and a negative contr ol population has not been identified. Methods: The work was conducted in two phases on two large farms in central Kenya during routine culls. The larynges of 42 zebra were removed and the left and right intrinsic laryngeal adductor and abductor muscles and recurr ent laryngeal nerves were isolated. The muscles were weighed and biopsy sam ples of left and right recurrent laryngeal nerve and cricoarytenoideus late ralis muscles from 16 animals were taken for histological examination. Results: Left adductor muscles were observed to be significantly lighter th an right adductor muscles (p = 0.001). There was no significant difference between the weights of left and right laryngeal abductors (p = 0.260). Ther e was no light microscopic evidence of pathological changes consistent with ILH in any of the muscle or nerve samples. Conclusions: Zebra do not appear to suffer from ILH and equids unaffected b y ILH can have significantly lighter muscles on the left of the larynx. Clinical relevance: Mild asymmetries of the larynx on palpation may not be a reliable indicator of ILH. Zebra may be a potentially useful negative con trol animal for observational ILH studies.